1. Field of the Invention
The invention relates to a method and apparatus for fluid flow control. More specifically, the invention relates to splitting a fluid flow such as a gas flow into pre-selected proportions.
2. Background of the Related Art
A chip manufacturing facility is composed of a broad spectrum of technologies. Cassettes containing semiconductor substrates are routed to various stations in the facility where they are either processed or inspected. Semiconductor processing generally involves the deposition of material onto and removal (xe2x80x9cetchingxe2x80x9d) of material from substrates. Typical processes include chemical vapor deposition (CVD), physical vapor deposition (PVD), electroplating, chemical mechanical planarization (CMP), etching and others.
Conventional substrate processing systems often process substrates serially, ie., one substrate at a time. Unfortunately, processing substrates serially results in throughput limitations corresponding to an individual substrate process time. To overcome the limitations of serial processing, batch (i.e., parallel) processing is often employed. Batch processing allows several substrates to be processed simultaneously using common fluids such as process gasses, chambers, processes, etc. thereby decreasing equipment costs, and increasing throughput. Ideally, batch-processing systems expose each of the substrates to an identical process environment whereby each substrate receives the same process gases and plasma densities for uniform processing of the batch.
One method for batch processing is performed in large single chamber batch-processing systems designed to accommodate more than one substrate. Unfortunately, as the substrates within a single batch-processing chamber share a common area, process gasses and plasma dedicated to one substrate will often intermix with the process gases and plasma dedicated to another substrate causing process variations within each substrate batch. To minimize the intermixing issue, internal chamber divider walls may be used that form sub-chambers within the single batch-processing chamber. However, chamber divider walls increase the cost and complexity of the batch-processing chamber. To eliminate the need for divider walls, multiple single-substrate processing chambers in tandem are often used to provide the benefits of batch processing and uniformity while allowing the careful control and isolation of the process environment for each substrate within a batch.
To control the individual process for each substrate within a batch-processing environment, individual gas, power, and plasma systems are often incorporated within the processing chambers or sub-chambers. In addition, there is usually an individual gas delivery system for each gas or mixture of gases. To reduce the cost of multiple gas supplies and process controls each individual processing region generally has common gas connections and sources. For example, the gas supplies for each sub-chamber or single-substrate processing chamber generally are coupled to a common gas source eliminating the need for multiple gas sources for the same gas or mixture of process gases. Unfortunately, due to variations in gas flow within each individual gas delivery system, each gas delivery system must be individually monitored and calibrated so that each substrate receives the same amount of process gas flow for each process step, according to the process regime. The variations in gas flow rates for each chamber are due to the flow resistance that depends upon the size of pipe used, length of pipe, and pipe joints, valves, etc. of the gas delivery systems.
To alleviate the calibration and control of each individual gas system for the single chamber or multi-chamber types of batch-processing systems, a centralized gas control system is often used to monitor and control the gas flow. Unfortunately, centralized gas control systems generally increase the complexity and cost of the processing systems. Thus, regardless of the batch processing system used, conventional individual gas delivery systems are often complex, require individual or centralized monitoring, require individual calibration, and generally increase the cost of production.
Therefore, there is a need for method and apparatus to provide a uniform fluid flow to each chamber within a batch-processing system in a simple and cost effective manner.
Aspects of the invention generally provide a fluid delivery system for controlling and dividing fluids such as process gases used in substrate processing. In one embodiment, the invention provides an apparatus for dividing a gas flow from a gas source, including a first gas line connected to a gas source, a gas flow meter positioned on the first gas line to output a signal corresponding to a gas flow rate through the first gas line, a second gas line connected to the gas source, and a gas flow controller positioned on the second gas line and responsive to the signal from the gas flow meter to divide the gas flow from the gas source.
In another embodiment, the invention provides an apparatus for dividing a gas flow from a gas source output into a tandem-processing chamber, including a first gas line connecting a gas source output to a first processing region of a tandem processing chamber, a gas flow meter positioned on the first gas line to output a signal corresponding to a first gas flow rate through the first gas line, a second gas line connecting the gas source output to a second processing region of the tandem processing chamber, and a gas flow controller positioned on the second gas line and responsive to the signal from the gas flow meter to divide the gas from the gas source output between the first gas flow rate through the first gas line to the first processing region and a second gas flow rate through the second gas line to the second processing region.
In still another embodiment, the invention provides a method of dividing a fluid flow from a fluid source, including measuring a first fluid flow rate through a first fluid line connected to the fluid source, and controlling a second fluid flow rate through a second fluid line connected to the fluid source using the first fluid flow rate through the first fluid line.
In another embodiment, the invention provides a method of dividing a gas flow in a tandem processing chamber including measuring a first gas flow rate from a gas source through a first gas line coupled to a first processing region of a tandem processing chamber, and using the first gas flow rate, controlling a second gas flow rate from the gas source through a second gas line coupled to a second processing region of the tandem processing chamber.